Airfoil Impingement Cooling with Zone-Specific Hole Density
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Solution Overview
Problem
Existing gas turbine engines face inefficiencies in cooling hot gas path components due to increased thermal resistance and reduced performance from thicker sidewalls and excessive bleed air extraction, which complicates heat removal from disparate temperature regions within the airfoil.
Innovation Solution
An airfoil design incorporating an impingement system with varying impingement hole density and compartmentalized post-impingement zones allows for tuned coolant flow velocity, pressure drop, and heat transfer coefficients to match local heat removal requirements, reducing the need for excessive bleed air and enhancing cooling efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the sidewall thickness of the airfoil is increased to increase cooling air flow velocity through the trailing edge, then heat transfer from the trailing edge is facilitated, but thermal resistance of the surfaces to be cooled increases
Solution Approach 1:
The airfoil cooling system is segmented into multiple independent cooling zones (leading edge zone, trailing edge zone, pressure sidewall zone, suction sidewall zone) with separate cooling passages and impingement hole patterns for each zone. This allows optimized cooling for each region without increasing overall sidewall thickness, thereby reducing thermal resistance while maintaining effective heat transfer.
Solution Approach 2:
Different impingement hole density patterns are provided for different zones of the airfoil exterior wall. The leading edge zone has a first impingement hole density pattern while the trailing edge zone has a second pattern, allowing each zone to receive optimized cooling flow velocity and distribution tailored to its specific thermal requirements without uniformly thickening the entire sidewall.
2Temperature
If additional bleed air is extracted from the compressor to increase cooling air flow velocity, then cooling efficiency is improved, but gas turbine engine efficiency is reduced
Solution Approach 1:
The system changes the distribution parameters of cooling air flow by providing varying impingement hole densities across different zones rather than uniformly distributing flow. This allows optimized heat transfer coefficients and flow velocities to be achieved with the same or less bleed air extraction, thereby maintaining gas turbine engine efficiency while improving cooling effectiveness.
3Ease of manufacture
If a uniform impingement hole density is used across the entire airfoil, then manufacturing is simplified, but heat transfer effectiveness in disparate temperature regions is reduced
Solution Approach 1:
The impingement system incorporates varying hole density patterns tailored to local thermal requirements: the leading edge zone has a first impingement hole density pattern optimized for high heat flux, while the trailing edge zone has a second pattern optimized for its thermal characteristics. This localized optimization maximizes heat transfer effectiveness in each region while maintaining manufacturability through standardized impingement hole fabrication processes.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This design maintains a consistent airfoil temperature, reduces thermal stresses, increases coolant stream efficiency, and enhances overall gas turbine engine efficiency by minimizing bleed air extraction while effectively cooling traditionally difficult-to-cool regions.
Implementation Method 1
an impingement system including an interior wall substantially parallel to the exterior wall. The interior wall defines a second interior space and a plurality of impingement holes configured to channel a flow of coolant from the second interior space to the first interior space
Implementation Method 2
The impingement system is configured to channel a coolant stream to the exterior wall... effectively cooling traditionally difficult-to-cool regions
Implementation Method 3
The interior wall having an impingement hole density having a varying hole density pattern. The impingement hole density configured to separately meter flow to the first and second zones
Implementation Method 4
a plurality of dividing walls extending from the interior wall to the exterior wall. The interior wall, the exterior wall, and the plurality of dividing walls define a first zone and a second zone
Data Source
AI summary
An airfoil includes an exterior wall, a trailing edge pin bank, and an impingement system. The exterior wall includes an inner surface and an outer surface and defines a first interior space. The impingement system is disposed within the first interior space and is configured to channel a coolant stream to the exterior wall. The coolant stream has a velocity. The impingement system includes an interior wall which defines a second interior space and a plurality of impingement holes having an impingement hole density. The impingement system also includes dividing walls extending from the interior wall to the exterior wall. The interior wall, exterior wall, and dividing walls define a first and second zone. A first dividing wall is coupled to the trailing edge pin bank and separates the first and second zones. The impingement hole density configured to separately meter flow to the first and second zones.